fix(ingest): databricks - ingest structs correctly through hive

metadata-ingestion/src/datahub/ingestion/source/sql/hive.py

@@ -1,4 +1,5 @@
 import json
+import logging
 import re
 from typing import Any, Dict, List, Optional
 
@@ -33,10 +34,62 @@
 from datahub.utilities import config_clean
 from datahub.utilities.hive_schema_to_avro import get_avro_schema_for_hive_column
 
+logger = logging.getLogger(__name__)
+
 register_custom_type(HiveDate, DateTypeClass)
 register_custom_type(HiveTimestamp, TimeTypeClass)
 register_custom_type(HiveDecimal, NumberTypeClass)
 
+try:
+
+    from databricks_dbapi.sqlalchemy_dialects.hive import DatabricksPyhiveDialect
+    from pyhive.sqlalchemy_hive import _type_map
+    from sqlalchemy import types, util
+    from sqlalchemy.engine import reflection
+
+    @reflection.cache  # type: ignore
+    def dbapi_get_columns_patched(self, connection, table_name, schema=None, **kw):
+        """Patches the get_columns method from dbapi (databricks_dbapi.sqlalchemy_dialects.base) to pass the native type through"""
+        rows = self._get_table_columns(connection, table_name, schema)
+        # Strip whitespace
+        rows = [[col.strip() if col else None for col in row] for row in rows]
+        # Filter out empty rows and comment
+        rows = [row for row in rows if row[0] and row[0] != "# col_name"]
+        result = []
+        for (col_name, col_type, _comment) in rows:
+            # Handle both oss hive and Databricks' hive partition header, respectively
+            if col_name in ("# Partition Information", "# Partitioning"):
+                break
+            # Take out the more detailed type information
+            # e.g. 'map<int,int>' -> 'map'
+            #      'decimal(10,1)' -> decimal
+            orig_col_type = col_type  # keep a copy
+            col_type = re.search(r"^\w+", col_type).group(0)  # type: ignore
+            try:
+                coltype = _type_map[col_type]
+            except KeyError:
+                util.warn(
+                    "Did not recognize type '%s' of column '%s'" % (col_type, col_name)
+                )
+                coltype = types.NullType  # type: ignore
+            result.append(
+                {
+                    "name": col_name,
+                    "type": coltype,
+                    "nullable": True,
+                    "default": None,
+                    "full_type": orig_col_type,  # pass it through
+                }
+            )
+        return result
+
+    DatabricksPyhiveDialect.get_columns = dbapi_get_columns_patched
+except ModuleNotFoundError:
+    pass
+except Exception as e:
+    logger.warning(f"Failed to patch method due to {e}")
+    pass
+
 
 class HiveConfig(BasicSQLAlchemyConfig):
     # defaults